(H2O, NH3, HF, CH4) is a stronger acid due to (hybridization, more electronegative atoms, size, electronegativity)
(HF, HBr, HI, HCl) is a stronger acid due to (other reasons, electronegativity, size of acid, hybridization)
(H-Br, H-Cl, H-I, H-F) is a stronger bond due to (bond overlapping, other readons, steric hindurance, electronegativity)